Refrigerant metering device



Oct. 1, 1963 F. w. OSBORN REFRIGERANT METERING DEVICE Filed Oct. 6, 1961 Jet wade! fiarzcr ((1 (936617? United States Patent ce Kansas Filed Oct. 6, 1961, Ser. No. 143,383 3 Claims. (Ci. 62-511) This invention relates to a refrigerant metering device, and more specifically, to an improved refrigerant metering device particularly suitable for use in conjunction with room air conditioning systems.

An object of the present invention is to provide a refrigerant metering device in which there is a relatively slight amount of variation in the flow of refrigerant therethrough as a result of changes in evaporator loading as compared with the flow variations in units of conventional design. Another object is to provide 'a refrigerant metering device in which refrigerant is pro-chilled prior to entering an evaporator, thereby increasing the effectiveness of an air-cooling unit.

Another object is to provide a metering device for air conditioners which is readily removable and replaceable and may thus he quickly replaced along with :a filter dryer should replacement of such parts be required because of compressor burn-out or because of any other reason. In this connection, it is a specific object to provide a refrigerant metering device which may be installed and removed, with or without the associated filter dryer, by a serviceman located on one side of the wall or Window through which a room air conditioning unit extends.

Other objects will appear from the specification and drawings in which:

FIGURE 1 is a perspective view of a room air conditioning unit, the side wall of the unit being broken away to illustrate the refrigerant metering device of the present invention;

FIGURE 2 is an enlarged longitudinal sectional View of the refrigerant metering; device;

FIGURE 3 is a top plan view of the device;

FIGURE 4 is an enlarged broken elevational view taken partly in section mid showing the attachment between the refrigerant metering device and a filter dryer.

In the structure illustrated in FIGURE 1, the numeral generally designates a room air conditioning unit having an inner section 11 adapted to be disposed within a room and an outer section 12 adapted to be disposed outside of the building or other enclosure to which the unit is secured. A partition 13 separates the chambers of the two sections and, when the unit is properly installed, coincides generally with the plane of the wall or window through which the air conditioner extends.

The casing of the air conditioner includes top, bottom and side walls 1416 respectively. One of the side Walls 16 is divided and the section 17 thereof which extends along the outer section 12 is removable to expose the mechanism of the unit for repair, cleaning or adjustment. If desired, the removable side panel or wall portion 17 may be slidably supported in the channels defined by opposing flanges 18 and 19.

Within the casing are the following typical components of an air conditioning unit: a compressor 20, an evaporator 21, a blower 22, and a refrigerant filter and dryer 23. The unit is also provided with a motor for driving the compressor and blower, and a condenser. While neither the motor nor the condenser are shown in FIGURE 1, such components are entirely conventional and constitute no part of the present invention. Accordingly, it is believed that further description of the parts so far mentioned is unnecessary for purposes of this application.

Between the condenser coil (not shown) located within section 12 adjacent grill 24 and evaporator 21 located in 3,i5,3ii7 Patented Dot. 1, 1953 Li section 11 are passage means for the flow of liquid refrigerant. This passage means includes conduit 25 eX- tending between the condenser and the filter-dryer 23 and also includes refrigerant metering device 26 extending between the filter-dryer and [the evaporator.

In the illustration given, the refrigerant metering device 26 comprises a pair of capillary tubes 27 each disposed within an evaporator inlet tube 28, the two inlet tubes in turn being covered by an insulated sheath 29. As shown most clearly in FIGURES 2 and 3, the evaporator inlet tubes 28 are straight and parallel and slope downwardly away from the evaporator at an angle within the range of about two to eight degrees. An angle of about five degrees has been found particularly effective. Except for their rounded and sealed end portions 39, the evaporator inlet tubes are disposed entirely within section 11 of the casing or cabinet. As indicated in FIGURE 1, end portions 30 project through partition 13 into the chamber section 12.

An end portion of each capillary tube 27 is telescoped within an inclined inlet tube 28. The external diameter of the capillary tube is substantially less than the internal diameter of the inlet tube so that an elongated annular space 31 is provided between the tubes. The straight end portion of the capillary tube extends substantially the full length of the inclined inlet tube in which it is received. The two concentric tubes 27 and 28 are secured together by solder 32 or other sealing means at the point where the capillary tube passes through the apertured and rounded end of an evaporator inlet tube.

Referring to FIGURE 4, it will be noted that the opposite ends of the capillary tubes 27 are secured within the crimped end of a coupling tube 33. The lower end of the coupling tube is crimped longitudinally along line 34 so that the two inserted ends of the capillary tubes will be held firmly in place but their passages will not be closed or obstructed. A coupling nut 35 is rotatably mounted upon the flanged opposite end of the coupling tube 33 and is internally threaded for attachment to the outlet nipple 36 of the refrigerant filter and dryer 23. The filter-dryer is entirely conventional and is of the molecular sieve type. Its cylindrical body 37 is held stationary 'by a mounting strap 38 which is fixed to partition 13 by mounting screws 39.

In the operation of the described structure, liquid refrigerant flows from the condenser through conduit 25 and into the dryer-filter unit 23 where impurities and moisture are removed therefrom. The refrigerant then passes into the capillary tubes 27 and finally into the inclined straight portions of the capillary tubes which are disposed within evaporator inlet tubes 28.

As liquid refrigerant is discharged from the ends of the capillary tubes a small proportion of the discharge tends to flow back down along the inside surfaces of the inclined portions of inlet tubes 28. Vaporization of refrigerant Within the elongated annular space 3 1 of each inlet tube withdraws heat from the enclosed portion of each capillary tube and thereby pre-cools the liquid refrigerant carried by the capillary tubes. Such an arrangement has been found particularly advantageous because the extent of restriction of refrigerant flow imposed by the capillary tubes will not vary as much with conditions of evaporator loading as in the conventional suction line to capillary tube heat exchange relationship. The reduction of refrigeration capacity at either extreme of the evaporators temperature range is relatively slight, an advantage which is particularly important in residential air conditioning systems where high capacities are desired at such extremes in 'order to provide a rapidly responding system regardless of conditions Within the space.

An important aspect of the invention lies in the ease with which the metering device may be replaced or repaired. Coupling nut 35 and soldered connections 32 are fully exposed on the same side of partition 13 when side panel 17 is removed. By simply heating the soldered connections 32 and by unthreading the coupling nut 35 the capillary tubes may be released from the inlet tubes and the filter-dryer and may be removed completely from the unit. Attachment of a repaired or a replacement part is the reverse procedure. Thus, the capillary tubes may be quickly replaced should compressor burn-out or any other occurrence or condition require such replacement. If desired, the filter-dryer may also be removed for cleaning or replacement at the same time that the capillary tubes are removed. To accomplish this, the connection between the filter-dryer and the capillary tubes is lefit intact and the filter-dryer is uncoupled at its upper end from conduit 25.

While in the foregoing l have disclosed an embodiment oi the present invention in considerable detail for purposes of illustration, it will be understood by those skilled in the art that many of these details may be varied without departing from the spirit and scope of the invention.

I claim:

1. In an air conditioning unit having an evaporator and a condenser, a refrigerant metering device comprising at least one substantially stnaight evaporator inlet tube having an elongated end portion sloping gradually upwardly towards said evaporator, said straight end portion of said inlet tube containing an elongated straight end portion of a capillary tube communicating with said condenser, said straight end portion of said capillary tube being of substantially the same length as said portion of said inlet tube and 'havin an external diameter substantially less than the internal diameter of said inlet tube, said inlet tube being sealed at its end to the outer surface oi said capillary tube and said capillary tube being positioned and arranged to direct fluid away from the sealed end of said inlet tube.

2. The structure of claim 1 in which said inlet tube is sealed at its end to the outer surface of said capillary tube by solder.

3. The structure of claim 1 in which said refrigerant metering device comprises a plurality of evaporator inlet tubes having substantially straight and sloping end portions each containing the end portion of acapillary tube, and an insulating sheath extending about the straight sloping portions of all of said inlet tubes.

References Cited in the file of this patent UNETED STATES PATENTS 1,866,659 Litle July 12, 1932 2,950,608 Abbott Aug. 30, 1960 2,956,421 Stevens Oct. 18, 1960 2,959,027 Ewing Nov. 8, 1960 2,990,698 Crotser July 4, 1961 

1. IN AN AIR CONDITIONING UNIT HAVING AN EVAPORATOR AND A CONDENSER, A REFRIGERANT METERING DEVICE COMPRISING AT LEAST ONE SUBSTANTIALLY STRAIGHT EVAPORATOR INLET TUBE HAVING AN ELONGATED END PORTION SLOPING GRADUALLY UPWARDLY TOWARDS SAID EVAPORATOR, SAID STRAIGHT END PORTION OF SAID INLET TUBE CONTAINING AN ELONGATED STRAIGHT END PORTION A CAPILLARY TUBE COMMUNICATING WITH SAID CONDENSER, SAID STRAIGHT END PORTION OF SAID CAPILLARY TUBE BEING OF SUBTANTIALLY THE SAME LENGTH AS SAID PORTION OF SAID INLET TUBE AND HAVING AN EXTERNAL DIAMETER SUBSTANTIALLY LESS THAN THE INTERNAL DIAMETER OF SASID INLET TUBE, SAID INLET TUBE BEING SEATED AT ITS END TO THE OUTER SURFACE OF SAID CAPILLARY TUBE AND SAID CAPILLARY TUBE BEING POSITIONED AND ARRANGED TO DIRECT FLUID AWAY FROM THE SEALED END OF SAID INLET TUBE. 